linux-kernel - Re: [PATCH RFC 0/2] mach-omap2: handle autoidle denial

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Date:   Thu, 4 Oct 2018 17:42:25 +0300
From:   Tero Kristo <t-kristo@...com>
To:     Tony Lindgren <tony@...mide.com>,
        Andreas Kemnade <andreas@...nade.info>
CC:     <mturquette@...libre.com>, <sboyd@...nel.org>,
        <linux-omap@...r.kernel.org>, <linux-clk@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <paul@...an.com>,
        <letux-kernel@...nphoenux.org>
Subject: Re: [PATCH RFC 0/2] mach-omap2: handle autoidle denial

On 04/10/18 17:25, Tony Lindgren wrote:
> * Andreas Kemnade <andreas@...nade.info> [181004 05:56]:
>> On the gta04 with a dm3730 omap_hdq does not work properly when the
>> device enters lower power states. Idling uart1 and 2 is enough
>> to show up that problem, if there are no other things enabled.
>> Further research reveals that hdq iclk must not be turned off during
>> transfers, also according to the TRM. That fact is also correctly described
>> in the flags but the code to handle that is incomplete.
>>
>> Since the order is first disable all autoidles, then disable selected
>> and then enable all, we need to either change that order or add
>> a usecount. Since it is done only in init, we could think about changing
>> order.
> 
> These patches look OK to me, assuming Tero will review them more
> closely.

There is no locking whatsoever in the autoidle counting atm, that must 
be fixed otherwise you get races.

> It seems we should just provide a generic interface for
> clk_allow_autoidle() and clk_deny_autoidle()? Otherwise we'll
> be forever stuck with pdata callbacks it seems.

The TI clock driver is actually providing these APIs, so that should be 
fine. I don't think there is any use / need for pdata callbacks atm, it 
just happens hwmod core is calling these at the moment which might have 
confused you.

-Tero
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